CDC Vaccine Advisers Vote to Stop Recommending Flu Shots That Contain Thimerosal

In a series of votes today, the CDC's new vaccine advisory committee voted to no longer recommend flu vaccines that contain thimerosal, a mercury-based preservative.

by Michael Nevradakis, Ph.D.

In a series of votes today, the CDC’s new vaccine advisory committee voted to no longer recommend flu vaccines that contain thimerosal, a mercury-based preservative linked to neurodevelopmental disorders.

The votes, part of a two-day meeting of the Advisory Committee on Immunization Practices (ACIP) that concluded today, took place after a presentation on the health risks of thimerosal by Lyn Redwood, a nurse practitioner with experience in pediatrics and family medicine.

Redwood, president emerita of Children’s Health Defense (CHD), presented as a private citizen. However, she will soon join the Centers for Disease Control and Prevention (CDC) in its vaccine safety office, multiple officials told CBS News.

Thimerosal is a preservative used in multidose vaccine vials to prevent the buildup of bacteria and fungi. It was removed from all routine childhood vaccines in 2001.

During her presentation, Redwood warned that mercury exposure “is a cumulative issue,” as the substance builds up in the body over time, including through repeated vaccination with shots containing the substance. She said it is “very feasible” to use alternative preservatives in single-dose vials.

ACIP voted separately on thimerosal-containing flu shots for children, pregnant women and adults. All three passed with a 5-1 vote and one abstention. The abstaining member, Vicky Pebsworth, Ph.D., a registered nurse, cited the vote’s wording, which did not make a distinction between recommending flu vaccines in general and recommending against multidose vials.

Dr. H. Cody Meissner, professor of pediatrics at Dartmouth’s Geisel School of Medicine, was the lone committee member to vote “no” for each of the three motions. “No study has ever indicated any harm from thimerosal,” he said.

In a separate vote, ACIP unanimously reaffirmed its recommendation for annual flu shots for all people 6 months and older who do not have contraindications.

In a statement following today’s votes, ACIP said, “We came to this meeting with no pre-determined ideas and will make judgements as if we are treating our own families. Unbiased scientific thinking is fundamental to the committee’s charge.”

Brian Hooker, Ph.D., chief scientific officer for CHD, called today’s outcome “a huge first step towards limiting toxic exposures especially to our most vulnerable individuals.”

Hooker said thimerosal “is still used in multidose vials of the flu shot, which have in the past comprised nearly half of all the flu shots given in the U.S., including those to pregnant women and infants down to age 6 months.”

According to CNN, most flu vaccines given in the U.S. come in single-dose vials that do not contain thimerosal, but around 4% come in multidose vials that do contain the preservative. Redwood cited data indicating that during the 2019-2020 flu season, over 60,000 pregnant women were vaccinated with multidose vials.

Today’s vote ‘20-plus years in the making’ — but concerns remain

Dr. Meryl Nass, who live-blogged today’s meeting for CHD.TV, wrote that the votes can be interpreted as a “yes for everyone getting a [flu] shot.”

Beth Clay, executive director of the International Chiropractors Association and a former congressional senior staffer who led the last comprehensive inquiry into issues related to vaccine injury, applauded ACIP’s vote, saying, “It’s 20-plus years in the making.”

However, she expressed concerns about the wording of today’s motions.

“I appreciate the clarification and education Pebsworth provided about the verbiage of the motions,” Clay said, suggesting that a vote on recommending an annual flu vaccine should have been held separately from a vote on the recommendation that flu vaccines offered to the public should be thimerosal-free.

“How you ask a question matters,” Clay said.

ACIP makes vaccine-related recommendations to the CDC director, who has the discretion to accept or reject them.

Until March, the agency’s acting director was Susan Monarez, Ph.D. She stepped down that month after President Donald Trump nominated her for the permanent director’s position.

Last month, U.S. Health and Human Services Secretary Robert F. Kennedy Jr. reported that attorney Matthew Buzzelli is currently acting director, while Monarez awaits U.S. Senate confirmation hearings.

Clay said that following today’s ACIP vote, the CDC may require the Vaccines for Children Program, a taxpayer-funded program providing vaccines to underprivileged children, to remove multidose flu vaccines and allow only the single-dose shots that don’t contain thimerosal. She suggested that today’s votes should have clarified that.

Thimerosal levels in flu vaccines 250 times higher than EPA safety limit

In the days leading up to this week’s ACIP meeting, several media outlets and medical organizations criticized Kennedy’s decision to dismiss the committee’s 17 former members earlier this month and appoint eight new members in their place.

Earlier this week, Sen. Bill Cassidy (R-La.), chair of the U.S. Senate’s Committee on Health, Education, Labor and Pensions, called for the postponement of this week’s ACIP meeting, citing concerns that its new members are biased against vaccines.

After the final agenda for this week’s ACIP meeting was published earlier in the week, media criticism turned to the inclusion of Redwood’s presentation on thimerosal, with CNN reporting that experts “found the inclusion of the topic on the ACIP agenda puzzling.”

The Guardian cited Dr. Paul Offit, director of the Vaccine Education Center and an attending physician in the Division of Infectious Diseases at Children’s Hospital of Philadelphia, who suggested there was no point in discussing thimerosal.

In a post on X Tuesday, Kennedy responded to a report by The Guardian last week characterizing thimerosal as safe, noting that thimerosal’s label advises against its use during pregnancy, and that thimerosal has “never been shown to be safe.”

Redwood’s presentation noted that thimerosal was first used as a vaccine preservative in the 1930s without any studies demonstrating its safety. The U.S. Food and Drug Administration (FDA) later “grandfathered” thimerosal as an approved vaccine ingredient without performing adequate safety testing.

Redwood said thimerosal has a 49.6% concentration of mercury — the third most toxic element for humans — and that thimerosal levels in flu vaccines are 250 times higher than the U.S. Environmental Protection Agency’s (EPA) safety limit.

“Thimerosal can cross the placenta and blood-brain barriers and converts to inorganic mercury in the brain,” Redwood said, noting that infants, young children, older adults, pregnant women and fetuses are particularly vulnerable to its effects.

Redwood, RFK Jr. push back at media claims that thimerosal is proven safe

Redwood’s presentation — and Kennedy’s X post — also addressed the mainstream media’s narratives by citing several studies that have demonstrated thimerosal’s risks to human health.

This included a 2001 Institute of Medicine report finding that the link between thimerosal and the rise of neurological conditions in children, including autism, is “biologically plausible.” The report recommended the termination of all vaccines containing thimerosal.

Redwood cited a 2005 primate study funded by the National Institutes of Health, which found that ethyl mercury — the type of mercury in thimerosal — more rapidly converted to inorganic mercury in the brain, resulting in increasing concentrations of inorganic mercury and subsequent neuroinflammation.

Redwood also cited a 2014 study finding that the half-life — the time needed for the concentration of a substance to be reduced in half — of inorganic mercury in the human brain ranges from five to 27 years. A 2016 study suggested there “may never be a safe level of mercury exposure, especially for an unborn child.”

Redwood also noted evidence contradicting claims that thimerosal is effective as a vaccine preservative and disinfectant. She cited a 2004 incident at a Fluvirin vaccine manufacturing plant, which was forced to close after it became contaminated with Serratia marcescens, a bacterium, even though the Fluvirin vaccine contained thimerosal.

According to Redwood, peer-reviewed studies published as far back as 1948 questioned the safety of thimerosal.

Kennedy suggested that The Guardian “did not bother to cite any peer-reviewed study” to support its claim that thimerosal is safe. Instead, The Guardian relied on “a fact check website operated by the Pharma-funded American Academy of Pediatrics” that “likewise cites no peer-reviewed study to support this claim or its equally terse assertion that ‘Thimerosal has been removed from all routine childhood vaccines.’”

In 2014, Kennedy authored “Thimerosal: Let the Science Speak,” in which he argued that there is a “broad consensus among research scientists that thimerosal is a dangerous neurotoxin.”

Thimerosal is cost-effective for vaccine manufacturers

Hooker agreed with Redwood and Kennedy’s conclusions. “Thimerosal is mercury, and mercury is, straight-up, a neurotoxin. This has been shown historically in thousands of publications.”

In 1998, growing concerns over thimerosal’s safety led the FDA to determine that thimerosal is “not generally recognized as safe and effective.” In 1990, California recognized thimerosal as a chemical known to cause cancer, birth defects or reproductive harm, under a state law known as Proposition 65.

According to Hooker, pharmaceutical companies continue to use thimerosal because it is cost-effective for them. He said:

“Thimerosal enables flu shot manufacturers to continue to manufacture multi-dose vials, which are cheaper per dose. It also has been used to quell the furor of countries overseas where many vaccines on the infant/child schedule still contain thimerosal.

“This is especially true in developing nations. They use the U.S. as an excuse for these companies to continue to peddle cheap and harmful vaccines overseas.”

Hooker called on public health agencies to enact “a complete ban of the use of thimerosal as a preservative for the manufacture and formulation of vaccines.”

Related articles in The Defender

• RFK Jr. Slams The Guardian for False Claims About Thimerosal in Vaccines

• Sen. Cassidy Calls for Delay of Vaccine Advisers Meeting, Criticizes RFK Jr.’s New Appointees

• RFK Jr. Taps 8 New ACIP Members, Offit Concedes Most ‘Seem Reasonable’

• RFK Jr.’s ‘Clean Sweep’ of CDC Vaccine Advisers Draws Mix of High Praise, Harsh Criticism

• Childhood Vaccine Schedule Led to ‘Greatest Decline in Public Health in Human History’